| | Question 4

Find the least perfect square number which when divided by 4, 6, 7, 9 gives remainder zero.

(A)

42

(B)

40

(C)

36

(D)

32

Answer: (A)
Explanation:

Find the LCM for 4, 6, 7, 9 
LCM= 2² * 3² * 7 = 252 
To become perfect square all factors should be in power of 2. 
So, multiply it by 7 LCM = 2² * 3² * 7² = 1764 
And it is perfect square of 42.

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